【摘要】 试验证明亚共析钢中魏氏组织的α铁系以贝茵体型相变的机构形成,相当于无碳贝茵体。奥氏体晶粒尺度、碳含量、温度以及冷却速度对魏氏组织的影响都很容易根据贝茵体形成机构的理论加以解释。更多还原

【Abstract】 The formation of Widmanst(a|¨)tten structure of alpha iron in hypoeutectoidsteels was investigated in 0.27,0.40,0.52 and 0.60% carbon steels.Specimenswere heated to 860° and 1240℃ in vacuo and cooled at different rates to roomtemperature or isothermally treated at various temperatures between 650° and750℃ in vacuo.It was shown that the Widmanst(a|¨)tten structure of alpha ironproduced in 0.27,0.40 and 0.52% carbon steels was always accompanied by asurface relief of the type associated with bainite transformation.The surfacerelief was not observed when conditions were not favourable for the productionof Widmanst(a|¨)tten structure.The effects of various factors on the formation of Widmanst(a|¨)tten structure ofalpha iron are discussed.It is suggested that the absence of Widmanst(a|¨)ttenstructure in slowly cooled specimens,and in specimens with fine austenitic grains,is due to the formation of grain boundary ferrite,which enriches the remainingaustenite with carbon,thereby prevents the formation of carbon-free bainite.The experimental results showed that austenite may decompose by bainitetransformation at temperatures as high as 750℃.更多还原